Surface treating apparatus



Jan. 17, 1950 w. H. MEAD ETAL 2,494,773

SURFACE TREATING APPARATUS Filed Nov. 13, 1948 2 Sheets-Sheet ,1

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62 s [4 ii 63 l ti L32 7 ATTORNEY Jan. 17, 1950 w. H. MEAD EIAL 2,494,773

SURFACE TREATING APPARATUS Filed Nov. 13, 1948 z'sheets-sheat 2 AIR SUPPLY npessse-o INVENTORS WILL/L4H H. MEAD ANDREW BUGHA/V QMZZw A 7' TORNEY' Patented Jan. 17, 1950 2,494,773 SURFACE TREATING APPARATUS William H. Mead, Oakland, and Andrew C. Buchau, San Francisco, Calif., assigno rs, by mesne assignments, to said Mead Application November 13, 1948, Serial No. 59,924

Claims. (0]. 51-8) This invention relates to surface-treating apparatus. In particular it relates to improvements in the operating head of an abrader in which the abrasive material is impelled against a working area by a strong pressure blast and is then removed from the working area along with the abraded particles by an even stronger suction current, for collection in a receptacle.

This invention is particularly well suited to solve the problem of cleaning machinery having uneven or relatively intricate surfaces, such as tire molds and the like. Ordinary abrasive cleaning devices widely scatter the grit and abraded particles in the vicinity of the object being cleaned. This is not only a hazard, but considerable time must be spent in cleaning up the debris once the abrasive operation is complete. An alternative abrading method is to place the piece being cleaned within a blast cabinet, but this technique is obviously of limited application and is somewhat impractical at best.

The problem has been how to provide a mobile abrader which could be brought to the machinery or other object to be cleaned and there clean it in place, but with th simultaneous collection of all the abrasive particles and debris. This problem was solved in a general way by the apparatus described in copending applications, Serial No. 608,386, filed August 2, 1945 which matured as Patent Number 2,455,514 on December 7, 1948, Serial No. 768,198, filed August 12, 1947 now abandoned, and Serial No. 778,378, filed October 7, 1947. However, the operating head (sometimes described as a gun) of the unit described in said applications, is not particularly well adapted for use with uneven or non-planar surfaces such as those present on tire molds, for example.

Further, in the unit described in said applications, the mounting of the blast and suction lines leading to the operating head is entirely separate, and for that reason manipulation of the head is made relatively cumbersome; it would be more convenient if a single connection could be used in the vicinity of the head.

It is therefore an object of this invention to provide an improved operating head for use with an abrader of the type which simultaneously blast-impels and suction-removes the abrasive with impinging air currents drawn in through the air pervious skirt.

Another object of this invention is to provide an operating head of the foregoing variety which can be used in treating uneven, curved, or irregular surfaces, particularly those having small crevices, as the interior of tire molds.

A further object of this invention is to provide an operating head which can be adjusted to vary the area and intensity of abrasive impingement, the adjustment also compensating for wear of parts and for different types of surface-treating materials which may be employed.

Other objects and advantages of this invention will appear in the course of the following description given in accordance with U. S. Revised Statutes Sec. 4888, thoughwithout intending to limit the scope of the invention otherwise than as claimed.

In the drawings:

Fig. 1 is a view in elevation and in section of an operating head which embodies the principles of this invention; for purposes of clarity the bristles in the rear are omitted, although they encircle the head as shown in Fig. 2;

Fig. 2 is a reduced bottom plan view, looking up into the open mouth of the head shown in Fig. l; and

Fig. 3 is a view in elevation, somewhat schematic in nature, showing a surfacetreating apparatus of the type with which the operating head of Fig. 1 may be used.

A brief description of the surface-treating apparatus illustrated in Fig. 3 will be helpful in understanding the principles of they improved operating head which is generally shown at It therein. An air compressor ll furnishes a stream of highly compressed air to the duct It. In a manner fully described in the aforesaid application Serial No. 608,386, which matured as Patent No. 2,455,514 on December 7, 1948, the abrasive is fed into this air-stream from a hopper 13 through a valve 14, a conduit I5 then carrying this abrasive-filled air-stream to the operating head I. where the abrasive particles impinge on the surface "5 to be cleaned. A powerful suction pump 2|] is also connected to the operating head l8 by a series of conduits through which the spent abrasive and any waste particles dislodged thereby are drawn back into the unit and are prevented from passing outwardly of the head In into the atmosphere. Specifically, the waste and spent abrasive are carried away from the head through a conduit 2| to a reclaimer 22 (described in the co-pending application, Serial No. 778,378) where any re-usable abrasive material is separated from the waste and passed into an upper hopper H from which it is periodicallydischarged into the main feed hopper l3. The waste is sucked out from the reclaimer 22 through a conduit 241 into a dust collecting bin 25.

Generally, this present invention comprises operating head l which serves to direct against a surface IE to be cleaned the abrasive or other treating material supplied by the unit described, and which thereafter facilitates the withdrawal of the abrasive and waste particles from the surface l6 and back into the unit before they can escape to the surrounding areas and go into the atmosphere.

This operating head comprises means to direct a blast of abrasive against a surface and suction means to remove the spent abrasive and the waste matter from the surface. A brush encircles the mouth of the head to provide an airpermeable maze which permits outside air to pass into the suction current, which is stronger than the blast current. The brush also traps abrasive and waste inside the head and serves to prevent it from spilling outside, holding it until it can be removed by the suction current. Concentrically arranged inside the brush is an impermeable flexible spacer ring having air-passage notches cut around its lower end. As will be seen, this flexible ring serves at once to space the nozzle ,housing from the surface being cleaned, protect the brush, and limit the inward passage of air to a thin, powerful stream.

The head Ill, shown in the drawings, is a preferred form of the invention, and it will now be described in detail. Its metal housing 30 has a straight-through vertical bore 3| open at both ends 32 and 33. An inclined side bore 34 communicates with the vertical bore 3| intermediate these ends 32 and 33 and at its own outer end 35 is detachably secured to the suction conduit 2|. Both bores 3| and 34 are lined with a layer 36 of rubber, which is bonded, as by vulcanization, to the housing 30.

The lower end 32 of the housing 30 faces the work surface I6 being cleaned. A hollow cap 40 slidesinto the upper end 33 of the housing and is secured there by set screws 4|. A fitting 42 is threaded into the cap 40 through the opening 43 adjacent its upper end. The other end of the fitting 42 is detachably connected with the blast hose l5. To permit different connections of the fitting 42 into the cap 40, additional openings 44 may be provided, with plugs 45 closing them when they are not in use.

A nozzle 50, preferably made from a very hard alloy, is threaded into the lower, interior end of the cap 40, snugly abutting a washer so as to provide a tight fit. The nozzle 50 extends inside the bore 3| but stops short of the housing's open end 32. At its upper end 52 the nozzle is funneled in toward a narrower neck portion 53. Below the neck 53 the nozzle mouth 54 is fiared outwardly so as to spread out the current of air and abrasive passing therethrough.

Slidably mounted around the lower end of the housing 30 is a collar 60, having a set screw 6| to fix it in any desired position with respect to the housing, as in co-pending application, Serial No. 28,858, filed May 24, 1948 which matured as concentrically arranged inside the brush 83 and also secured to the flange 32 is a flexible baflle 65, preferably made from natural or synthetic rubber. The baflle 35 preferably comprises a series of stepped rings, as shown in the drawing, which may beseparate rings secured together or may be molded integrally as steps. Its full thickness (or the total thickness of all the rings) extends a short distance below the open end 32; then it is radially oflset successively at 66 and 61. The thin lowermost portion 58 of the baiile is shaped to provide air passage inlets, such as the notches 10.

In operation, the abrasive is carried from the hose l5 by the air blast into the cap 40. From there it passes through the nozzle 50, which impinges the abrasive against the surface Hi. The suction force being exerted is more powerful than the blasting force, so that air passes in through the brush 63 and the passages or notches Ill, gathers upthe waste and the spent abrasive and carries it out around the nozzle 50 into the bore 34 from where it is carried into the suction hose 2|.

The impermeable baiiie 65 above the notches prevents the inward passage of air, and confines the air to the concentrated current passing through the notches I0. Moreover, the brush 63 is protected from the wearing action of the abrasive by the baflie 65. Since the baille 65 is made of flexible material, the head readily adapts itself to changes and irregularities in surfaces.

What is claimed is:

1. In an operating head for a blast-impelling, suction-removing, surface-treating apparatus, said head including a hollow housing open at its lower end where it faces the work surface, the bore of said housing also being in communication with a suction line and having means therein connected with a blast line and for directing said blast out through said lower end, the combination therewith of a circular brush secured around the lower end of said housing to provide a maze-like, air-permeable, impeding means and an inner impermeable member secured around said housing between said housing and said brush, said member having air passages through its lower periphery.

2. The head claimed in claim 1 in which said impermeable member is made from a resilient material.

3. The head claimed in claim 2 in which said impermeable member is thicker at its upper end than at its lower end, whereby it is more flexible at its lower end.

4. The head claimed in claim 1 in which the bore of said housing is protected by an inner lining of rubbery material bonded to said housing.

5. The head claimed in claim 1 in which the brush and the impermeable member are secured to a collar which is slidable around said housing for adjustment with respect thereto.

WILLIAM H. LIEAD.

ANDREW C. BUCHAN.

No references cited. 

